Is it possible to use "Animation Nodes" when exporting it to a game engine?
As Duarte Correctly pointed out, animation nodes are Blender exclusive data. If you use a format that supports animations, such as Collada or Alembic, you should be able to export the animations as keyframe animations. However, this will only work for the basic location-rotation-scale animations, things like mesh deformations created with animation nodes will not be exported. A similar question has been asked here if you want a bit more info: Blender page animation collada file in Scenekit

If you have any issues, you can also check out this question that the creator of the addon answered: Convert Animation Nodes to Object and Keyframes